A brief analysis of the angular learning path by module

This article will take you to understand the routing module in angular, and introduce related knowledge such as matching rules, routing parameters, routing nesting, named sockets, navigation routing, routing lazy loading, etc. I hope it will be helpful to you. Everyone helps!

In Angular, routing is based on modules, and each module can have its own route. [Related tutorial recommendations: "angular tutorial"]

Get started quickly

---

1. Create page components, Layout components and Navigation components , for routing use

• Create

  HomepagePage componentng g c pages/home

##Create
• About us

  Page componentsng g c pages/about

Create
• Layout

  Componentng g c pages/layout

Create
• Navigation

  Componentng g c pages/navigation

2. Create routing rules

// app.module.ts
import { Routes } from "@angular/router"

const routes: Routes = [
  {
    path: "home",
    component: HomeComponent
  },
  {
    path: "about",
    component: AboutComponent
  }
]

3. Introduce the routing module and start

// app.module.ts
import { RouterModule, Routes } from "@angular/router"

@NgModule({
  imports: [RouterModule.forRoot(routes, { useHash: true })],
})
export class AppModule {}

4. Add

routing socket

<div class="code" style="position:relative; padding:0px; margin:0px;"><pre class="brush:js;toolbar:false;">&lt;!-- 路由插座即占位组件 匹配到的路由组件将会显示在这个地方 --&gt; &lt;router-outlet&gt;&lt;/router-outlet&gt;</pre><div class="contentsignin">Copy after login</div></div>5. In the navigation component Define links

<a routerLink="/home">首页</a>
<a routerLink="/about">关于我们</a>

Matching rules

---

## 1. Redirect

const routes: Routes = [
  {
    path: "home",
    component: HomeComponent
  },
  {
    path: "about",
    component: AboutComponent
  },
  {
    path: "",
    // 重定向
    redirectTo: "home",
    // 完全匹配
    pathMatch: "full"
  }
]

2. 404 page

const routes: Routes = [
  {
    path: "home",
    component: HomeComponent
  },
  {
    path: "about",
    component: AboutComponent
  },
  {
    path: "**",
    component: NotFoundComponent
  }
]

Route parameter

---

1. Query parameters

<a routerLink="/about" [queryParams]="{ name: &#39;kitty&#39; }">关于我们</a>

import { ActivatedRoute } from "@angular/router"

export class AboutComponent implements OnInit {
  constructor(private route: ActivatedRoute) {}

  ngOnInit(): void {
    this.route.queryParamMap.subscribe(query => {
      query.get("name")
    })
  }
}

2. Dynamic parameters

const routes: Routes = [
  {
    path: "home",
    component: HomeComponent
  },
  {
    path: "about/:name",
    component: AboutComponent
  }
]

<a [routerLink]="[&#39;/about&#39;, &#39;zhangsan&#39;]">关于我们</a>

import { ActivatedRoute } from "@angular/router"

export class AboutComponent implements OnInit {
  constructor(private route: ActivatedRoute) {}

  ngOnInit(): void {
    this.route.paramMap.subscribe(params => {
      params.get("name")
    })
  }
}

Routing nesting

Routing nesting instructions The is how

define child routing

---

.

<div class="code" style="position:relative; padding:0px; margin:0px;"><pre class="brush:js;toolbar:false;">const routes: Routes = [ { path: &quot;about&quot;, component: AboutComponent, children: [ { path: &quot;introduce&quot;, component: IntroduceComponent }, { path: &quot;history&quot;, component: HistoryComponent } ] } ]</pre><div class="contentsignin">Copy after login</div></div><div class="code" style="position:relative; padding:0px; margin:0px;"><pre class="brush:js;toolbar:false;">&lt;!-- about.component.html --&gt; &lt;app-layout&gt; &lt;p&gt;about works!&lt;/p&gt; &lt;a routerLink=&quot;/about/introduce&quot;&gt;公司简介&lt;/a&gt; &lt;a routerLink=&quot;/about/history&quot;&gt;发展历史&lt;/a&gt; &lt;div&gt; &lt;router-outlet&gt;&lt;/router-outlet&gt; &lt;/div&gt; &lt;/app-layout&gt;</pre><div class="contentsignin">Copy after login</div></div>

Named Outlets

Display child routing components into different routing outlets.

---

{
  path: "about",
  component: AboutComponent,
  children: [
    {
      path: "introduce",
      component: IntroduceComponent,
      outlet: "left"
    },
    {
      path: "history",
      component: HistoryComponent,
      outlet: "right"
    }
  ]
}

<!-- about.component.html -->
<app-layout>
  <p>about works!</p>
  <router-outlet name="left"></router-outlet>
  <router-outlet name="right"></router-outlet>
</app-layout>

<a
    [routerLink]="[
      &#39;/about&#39;,
      {
        outlets: {
          left: [&#39;introduce&#39;],
          right: [&#39;history&#39;]
        }
      }
    ]"
    >关于我们
</a>

Navigation routing

<!-- app.component.html -->
 <button (click)="jump()">跳转到发展历史</button>

// app.component.ts
import { Router } from "@angular/router"

export class HomeComponent {
  constructor(private router: Router) {}
  jump() {
    this.router.navigate(["/about/history"], {
      queryParams: {
        name: "Kitty"
      }
    })
  }
}

Routing module

---

Abstract the routing configuration in the root module into a separate The routing module is called

root routing module

---

, and then the root routing module is introduced in the root module.

<div class="code" style="position:relative; padding:0px; margin:0px;"><pre class="brush:js;toolbar:false;">import { NgModule } from &quot;@angular/core&quot; import { HomeComponent } from &quot;./pages/home/home.component&quot; import { NotFoundComponent } from &quot;./pages/not-found/not-found.component&quot; const routes: Routes = [ { path: &quot;&quot;, component: HomeComponent }, { path: &quot;**&quot;, component: NotFoundComponent } ] @NgModule({ declarations: [], imports: [RouterModule.forRoot(routes, { useHash: true })], // 导出 Angular 路由功能模块，因为在根模块的根组件中使用了 RouterModule 模块中提供的路由插座组件 exports: [RouterModule] }) export class AppRoutingModule {}</pre><div class="contentsignin">Copy after login</div></div><div class="code" style="position:relative; padding:0px; margin:0px;"><pre class="brush:js;toolbar:false;">import { BrowserModule } from &quot;@angular/platform-browser&quot; import { NgModule } from &quot;@angular/core&quot; import { AppComponent } from &quot;./app.component&quot; import { AppRoutingModule } from &quot;./app-routing.module&quot; import { HomeComponent } from &quot;./pages/home/home.component&quot; import { NotFoundComponent } from &quot;./pages/not-found/not-found.component&quot; @NgModule({ declarations: [AppComponent，HomeComponent, NotFoundComponent], imports: [BrowserModule, AppRoutingModule], providers: [], bootstrap: [AppComponent] }) export class AppModule {}</pre><div class="contentsignin">Copy after login</div></div>
Routing lazy loading

Routing lazy loading is based on

module

---

.

1. Create user module
ng g m user --routing=true

Create the routing module of this module together

2. Create login page componentng g c user/pages/login

3. Create the registration page componentng g c user/pages/register

4. Configure the routing rules of the user module

import { NgModule } from "@angular/core"
import { Routes, RouterModule } from "@angular/router"
import { LoginComponent } from "./pages/login/login.component"
import { RegisterComponent } from "./pages/register/register.component"

const routes: Routes = [
  {
    path: "login",
    component: LoginComponent
  },
  {
    path: "register",
    component: RegisterComponent
  }
]

@NgModule({
  imports: [RouterModule.forChild(routes)],
  exports: [RouterModule]
})
export class UserRoutingModule {}

5. Associate the user routing module to the main routing module

// app-routing.module.ts
const routes: Routes = [
  {
    path: "user",
    loadChildren: () => import("./user/user.module").then(m => m.UserModule)
  }
]

6. Add access links in the navigation component

<a routerLink="/user/login">登录</a>
<a routerLink="/user/register">注册</a>

Route Guard

The route guard will tell the route whether navigation to the requested route is allowed.

---

The routing method can return
boolean

or

Observable or Promise , they Resolve as a Boolean value at some point in the future.

1. CanActivate

Check whether user can access a certain route

.

CanActivate is the interface

. The route guard class must implement this interface. The interface stipulates that the class needs to have a canActivate method, which determines whether to allow access to the target route.

Routing can apply Multiple guards

. Only if all guard methods are allowed, the route is allowed to be accessed. If one guard method is not allowed, then the route is not allowed to be accessed.

Create routing guards:ng g guard guards/auth

import { Injectable } from "@angular/core"
import { CanActivate, ActivatedRouteSnapshot, RouterStateSnapshot, UrlTree, Router } from "@angular/router"
import { Observable } from "rxjs"

@Injectable({
  providedIn: "root"
})
export class AuthGuard implements CanActivate {
  constructor(private router: Router) {}
  canActivate(): boolean | UrlTree {
    // 用于实现跳转
    return this.router.createUrlTree(["/user/login"])
    // 禁止访问目标路由
    return false
    // 允许访问目标路由
    return true
  }
}

{
  path: "about",
  component: AboutComponent,
  canActivate: [AuthGuard]
}

2、CanActivateChild

Check whether the user can access a certain sub-route.

Create routing guards: ng g guard guards/admin

Note: To select CanActivateChild, you need to move the arrow to this option and tap the space to confirm the selection.

import { Injectable } from "@angular/core"
import { CanActivateChild, ActivatedRouteSnapshot, RouterStateSnapshot, UrlTree } from "@angular/router"
import { Observable } from "rxjs"

@Injectable({
  providedIn: "root"
})
export class AdminGuard implements CanActivateChild {
  canActivateChild(): boolean | UrlTree {
    return true
  }
}

{
  path: "about",
  component: AboutComponent,
  canActivateChild: [AdminGuard],
  children: [
    {
      path: "introduce",
      component: IntroduceComponent
    }
  ]
}

3. CanDeactivate

## Check whether the user can exit the route.

For example, the content entered by the user in the form is not saved, and the user wants to leave the route. At this time, the guard can be called to prompt the user.

import { Injectable } from "@angular/core"
import {
  CanDeactivate,
  ActivatedRouteSnapshot,
  RouterStateSnapshot,
  UrlTree
} from "@angular/router"
import { Observable } from "rxjs"

export interface CanComponentLeave {
  canLeave: () => boolean
}

@Injectable({
  providedIn: "root"
})
export class UnsaveGuard implements CanDeactivate<CanComponentLeave> {
  canDeactivate(component: CanComponentLeave): boolean {
    if (component.canLeave()) {
      return true
    }
    return false
  }
}

{
  path: "",
  component: HomeComponent,
  canDeactivate: [UnsaveGuard]
}

import { CanComponentLeave } from "src/app/guards/unsave.guard"

export class HomeComponent implements CanComponentLeave {
  myForm: FormGroup = new FormGroup({
    username: new FormControl()
  })
  canLeave(): boolean {
    if (this.myForm.dirty) {
      if (window.confirm("有数据未保存, 确定要离开吗")) {
        return true
      } else {
        return false
      }
    }
    return true
  }

4. Resolve

Allows the data to be obtained before entering the routing, and then enters the routing after the data acquisition is completed.

ng g resolver

import { Injectable } from "@angular/core"
import { Resolve } from "@angular/router"

type returnType = Promise<{ name: string }>

@Injectable({
  providedIn: "root"
})
export class ResolveGuard implements Resolve<returnType> {
  resolve(): returnType {
    return new Promise(function (resolve) {
      setTimeout(() => {
        resolve({ name: "张三" })
      }, 2000)
    })
  }
}

{
   path: "",
   component: HomeComponent,
   resolve: {
     user: ResolveGuard
   }
}

export class HomeComponent {
  constructor(private route: ActivatedRoute) {}
  ngOnInit(): void {
    console.log(this.route.snapshot.data.user)
  }
}

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